Can hidden food or dairy allergies cause weight gain?

It sounds like a gag question, but stop and think about it. Do you feel bloated and way-too-full after you eat a scoop of ice cream? Are you gaining weight even though you are sticking to a low-calorie, low-fat diet? If so, hidden food or dairy allergies may be responsible. They can cause weight gain, the perception of weight gain -- namely gas and bloating that can make it hard to zip up your jeans, and other belly woes.

The good news is that a little detective work followed by some tweaking of your diet can have you feeling -- and looking -- much better in no time.

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Food allergies: rounding up the usual suspects

Traditional food allergies to foods like peanut and shellfish occur when your body's immune system misfires against a protein found in food. This "friendly fire" causes a release of chemicals, including histamine that can lead to allergic symptoms such rashes, hives, itching, swelling, and sometimes potentially fatal trouble breathing, or anaphylaxis. As many as 15 million people have food allergies, according to the Food Allergy & Anaphylaxis Network. Even more common are food intolerances or sensitivities.

"There are different ways a body responds adversely to food," says Mark Hyman, MD, founder and medical director of The UltraWellness Center in Lenox, Mass., and the author of many books including The Blood Sugar Solution. "There can be a full-blown allergic response like there would be with peanut allergy, and there can be a low-level reaction that is more of a sensitivity."

When we talk about weight gain, bloating, and general malaise associated with eating certain foods, we are talking about food sensitivities, Dr. Hyman says. This delayed allergy is known as an immunoglobulin G (IgG) delayed hypersensitivity reaction.

For a host of reasons, certain foods trigger inflammation in certain people, which in turn can cause anything and everything from weight gain and bloating to joint pain and even headache.

Common culprits include:

Lactose, the sugar found in milk or dairy products

Gluten, the main protein found in wheat and a few other grains

Fructose, the primary sugar in fruit juice, and honey, sodas, and other beverages containing high fructose corn syrup and alcohol

Corn

Eggs

Soy

Hidden food allergies: innocent until proven guilty

How can you find out if hidden food allergies or intolerances are what's eating you? Sharon Zarabi, RD, a nutritionist at Lenox Hill Hospital in New York City, often helps patients figure out precisely what ingredients trigger their symptoms. Here's how she does it:

Step 1. Keep a food diary

"List the specific foods you are eating -- even brand names -- and all of the symptoms that you experience afterward for one week," she says. For example, do you feel tired or bloated after eating cottage cheese or diet soda? Or crampy and constipated after a pasta meal? Whatever the symptom, write it down.

Step 2. Eliminate prime suspects

Next, she tells patients to steer clear of all of the foods that seem to be causing the symptoms for the next two weeks.

Step 3. Slowly re-introduce foods

Re-introduce foods one at a time to try to isolate the one(s) driving your symptoms, she says.

Hyman adds, "We can't just take away one thing. We take away everything and then add them back one at a time." Sometimes blood tests can help measure IgG food allergens, but these are not available everywhere and not always 100 percent reliable, he says.

Something about gluten: not quite celiac disease

Today, there is lots of talk about gluten and gluten sensitivity, not to mention a proliferation of gluten-free foods on market shelves.Gluten sensitivity or intolerance has different and less severe effects than celiac disease, explains Peter H. R. Green, MD, a professor of clinical medicine at Columbia University College of Physicians & Surgeons in New York City and the director of the Celiac Disease Center.

Celiac disease occurs when the body mistakenly attacks the small intestine and prevents it from absorbing gluten. More than two million people in the United States have celiac disease, according to the National Institute of Diabetes and Digestive and Kidney Diseases. But many more may have non-celiac glucose intolerance or at least think they do, he says. And this kind of food intolerance can make you feel bloated and fat, Dr. Green says.

He routinely suggests a simple hydrogen breath test for people who fall into this camp. "You come in and breathe into a machine," he says. Increased hydrogen production occurs when sugars are such lactose, sucrose, fructose, and sorbitol are not properly digested.

This test can also help determine is there is an imbalance of good and bad bacteria in the gut, which can also be causing your symptoms."We can see if it is fructose, lactose, another sugar, or bacterial overgrowth," he says."People say it's sugar or carbs that makes them feel bad, but it is usually more specific than that. If you are gaining weight or bloating, see a gastroenterologist and have a breath test done. The results can turn your life around." These intolerances may masquerade as gluten sensitivity or travel with it, he says.

Food allergy and weight gain or weight loss?

Not everyone is in agreement that food allergies cause weight gain. In fact, Scott H. Sicherer, MD, a professor of pediatrics at the Jaffe Food Allergy Institute of Mount Sinai School of Medicine in New York City and the author of several books including Food Allergies: A Complete Guide for Eating When Your Life Depends on It, says they are more likely to cause the opposite -- weight loss.

"Besides hives and wheezing, food allergies can cause chronic stomach problems and people may vomit, have diarrhea, and lose weight," he says. Also, it makes perfect sense that if you start eliminating whole groups of food -- say wheat products, for example -- you will probably lose weight, instead of gaining it.

Bloating is possible for people who have trouble digesting lactose, the sugar in milk. "This is not a dairy allergy per se," he says. "It is a digestive issue. Your belly may look more bloated, but you won't gain weight."

Marc Riedl, MD, an associate professor of medicine and section head of clinical immunology and allergy at the David Geffen School of Medicine at UCLA in Los Angeles, is another expert who doesn't buy into food allergies causing weight gain or bloating. "It's a pet peeve of mine," he says. "The media uses the term food allergy to mean anything unpleasant that happens when you eat a food." Food is often just an innocent bystander. "It gets blamed for a lot of things because we eat many times throughout the day, so food can almost certainly be closely approximated to any symptom we experience," he adds.

That said, many people may not feel well after they eat dairy foods or gluten. "This is not a life threatening problem, and making some simple dietary changes may make them feel better," Dr. Riedl suggests.